The preferred treatment for hydrocephalus involves the use of a catheter to drain cerebrospinal fluid from ventricles of the brain. The ventricles, normally large enough to easily accommodate the end of a catheter several millimeters in diameter, have pliable walls within which is found the choroid plexus, a soft, curtain-like tissue. The end of the catheter that is received within a ventricle commonly is provided with small holes through its walls for receiving cerebrospinal fluid from the ventricle. In order to restrain the choroid plexus from coming into contact with and plugging the holes, fins or other structure, as shown in U.S. Pat. No. 3,516,410 or U.S. Pat. No. 3,626,950, has been employed, the fins extending radially outwardly from the walls of the catheter and the holes within the catheter wall being formed between adjacent fins. Continued loss of cerebrospinal fluid may lead to collapse of the ventricles, the walls of the ventricles tending to shut upon one another as cerebrospinal fluid is lost through the catheter. Such ventricular wall collapse upon an indwelling catheter tends to also block the holes in the catheter wall, preventing further drainage of cerebrospinal fluid.
Perhaps the largest health hazard in the installation of ventricular catheters is that of infection. Infection most frequently results from skin contaminants, and infection commonly becomes evident within about seven to ninety days after a ventricular catheter is surgically implanted. The catheter, as a hollow foreign object, tends to provide suitable sites for microorganism growth, and in the event of an infection, removal of the catheter system is medically indicated.
Often some tissue growth onto or into a ventricular catheter occurs (aided, it would appear, by the presence of thin-walled discs or flanges intended to physically shelter the drainage holes through the catheter wall) and this, in turn, renders removal of the catheter extremely difficult. Sometimes the catheter can be moved only very slightly in an effort to dislodge connecting tissue. From a medical standpoint, a catheter which has become bound within a ventricle by fibrous adhesions or the like should not be removed forcefully; it is thought advisable in this situation to allow the catheter to remain in place rather than risk intraventricular hemorrhage. Accordingly, a choice must often be made between risking internal hemorrhage on the one hand or persistant infection on the other.